Silane terminated

Multiblock polyethylene-polydimethylsiloxane copolymers were obtained by the reaction of silane terminated PDMS and hydroxyl terminated polyethylene oligomers in the presence of stannous octoate as the catalyst 254). The reactions were conducted in refluxing xylene for 24 hours. PDMS block size was kept constant at 3,200 g/mole, whereas polyethylene segment molecular weights were varied between 1,200 and 6,500 g/mole. Thermal analysis and dynamic mechanical studies of the copolymers showed the formation of two-phase structures with crystalline polyethylene segments. 

Polystyrene-polydimethylsiloxane (PDMS) triblock (or multiblock) copolymers 123) can be made by hydrosilylation involving a vinyl silane terminated polystyrene and a PDMS fitted at both chain ends with Si—H groups. The former species is ob-... 

As an application of this methodology to the syntheses of natural products, Sannicolo et al. have reported the preparation of benzazepine and tetra-hydroisoquinoline derivatives by silane-terminated intramolecular Heck reactions. These workers argued that one main disadvantage of the Heck reaction... 

Scheme 7.4 Syntheses of benzazepines and tetrahydroisoquinolines by intramolecular silane-terminated Heck reactions with (T )-BITIANP and ( + )-TMBTP ligands.

Arrayed PDA liposomes have been prepared via microcontact printing of NHS ester-containing hposomes onto aminopropyl silane terminated glass surfaces... 

Hexenylsilane was introduced as a co-monomer into the organotitanium-mediated polymerization of ethylene to produce silane-terminated ethylene-5-hexenylsilane copolymers. High activities and narrow polydispersities were observed in the polymerization-chain transfer process. Ethylene-5-hexenylsilane copolymer molecular weights... 

Pohl, E. and Osterholz, F. D., Novel Vulcanizable Silane-Terminated Polyurethane Polymers, U.S. Patent 4,645,816, 1987. 

Heck reactions (99CC1811), but highly efficient for silane-terminated Heck reactions (00CC583). 

The general procedure for a silane-terminated intramolecular enantioselective Heck reaction is exemplified by Scheme 3-60 [61a,b, 259]. A mixture of [Pd2(dba)3 - CHCI3] (0.025 mmol,... 

Keywords spray foam, isocyanate free, silane terminated, prepolymers... 

Summary As all conventional spray foams contain monomeric isocyanates, they can present toxicological hazards. Therefore, an isocyanate-ftee substitute for these foams has been developed. This isocyanate-free foam is cured by a crosslinking reaction of silane-terminated prepolymers (STPs). This silane crosslinking system exhibits some new properties, and several problems occur that are completely unknown with ordinary isocyanate spray foams. In particular, crack formation during foam curing turns out to be a crucial problem. Therefore it was necessary to develop modified STPs and to use special STP-propellant mixtures. 

To develop toxicologically safe spray foams, it is necessary to find a curing reaction that does not involve isocyanates but is able to generate rigid foams from low-viscosity prepolymers. These conditions can be met by silane-terminated prepolymers (STPs). 

Poly(dimethylsiloxane) segments can also be introduced into the block copolymers as in B-99 to B-101, where the silane terminal of poly(dimethyl-... 

Lewis acid-catalyzed ene cyclization reactions at low temperature have been shown to yield substituted piperidines with a high diastereomeric ratio <05TL6611>. Organolanthanide-catalyzed cyclization-silylation has been developed as a powerful strategy for the piperidine rings found in alkaloids. As a prototypical example, the simple diallyl amine 174 was cyclized to 175 in the presence of 5 mol % of the catalyst shown in Scheme 50 and a suitable silane terminator <0512631>. 

Scheme 3-5 Silane-terminated intramolecular Heck reaction [61].

This transformation can also be achieved using malonates and P-keto ester nucleophiles. Tietze and Raschke have used a silane-terminated Heck reaction, in which the substrate (10.151) loses the silyl group to give the cyclised product (10.152). Incorporation of a nitrogen atom at the requisite position in the side chain allows the enantioselective synthesis of tetrahydroisoquinolines and benzazepines using this methodology. ... 

The engineers had formulated requirements as to how the desired adhesive layers should deform under a shear loading. These rules were very unusual because normally, engineers make no requirements at all they just test the adhesives offered by the adhesive company and then report if they are satisfied or not. The adhesive company found it difficult to meet the requirements. The most important characteristics required of the adhesive layer were the flexibility as well as the deformability. Obviously, traditional wood adhesive systems like vinyl acetate or formaldehyde-based adhesives could not be used because they only work in very thin adhesive layers. Furthermore, they are brittle and have virtually no mechanical flexibility. Thus only two technologies were considered as potential candidates polyurethanes (including silane-terminated types) and epoxies. 

CO-silane-Terminated Copolymers with Tunable Curing Rates... 

The following results give an overview of the possibilities of new silane-terminated polymers (STP) using isocyanatomethylalkoxysilanes (a-NCO-silanes) for endcapping. These STP systems show dramatically enhanced reactivities and curing rates. Furthermore two possible applications in new fast rtv-silicone copolymer systems were examined. 

Figure 2 shows the reactivity, measured as tack-free time in STP-S polymer systems (see below) of systems terminated with different NCO-silanes. The new a-silanes show dramatically enhanced curing rates. Additionally, the curing rates of compounds made from these polymers can be varied over a wide rage, using different amounts of catalyst (usually tin) and water scavengers (usually alkoxysilanes). Comparable results were achieved in silane-terminated polyethers and polyurethanes. 

Silane-terminated poiysiioxanes are a new class of high reactive rtv-1 silicone systems. The synthesis of these polymers is shown in Eq. 1. In a first step a hydroxy-terminated polydimethylsiloxane is converted to the corresponding aminopropyl-polydimethylsiloxane by reaction with stoichiometric amounts of 3-[(2,2-dimethyl-l,2-a2asiiolidin-l-yl)dimethylsilyl]-l -propylamine at room temperature. The silane termination reaction in a second step is carried out under the same conditions without adding further catalysts, due to the fast reaction of NCO groups with the primary amino groups. 

Table 4. Properties of silane-terminated siloxane-urea copolymers.

Suitable Silane-Terminated Prepoiymers for Spray Foam Appiications... 

The silane-terminated prepolymers are prepared from polypropyleneglycol (M = 450), TDI, and (N-phenylaminomethyl)trimethoxysilane (1 Fig. 3). 

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